Because of having various characteristics including low surface tension, good lubricating properties and mold releasing characteristics, high heat stability, low glass transition point and high gas permeability, organopolysiloxanes (hereinafter sometimes referred to as "silicones") have been widely employed in lubricating agents, heat media, electrical insulating materials, leveling agents for paints, mold releasing agents, cosmetic additives, fiber treating agents, shock absorbing materials, sealings, templating agents, glazing agents, foam stabilizers, defoaming agent, etc.
Among these, silicone oils are frequently employed as cosmetic additives in skin care products, foundations, shampoos, hair rinses, hair conditioners, mainly for improving texture. Silicone resins are also used in the form of spherical fine particles in skin care products.
Moreover, film-forming polymers are used in hair setting agents. However, the silicone polymers capable of forming a film would generally undergo crosslinkage via covalent bonding, which restricts the solvent types usable therefor. These silicone bases have another disadvantage that they cannot be easily washed away, when employed in skin or hair care products. On the other hand, hydrophilic silicone emulsions are highly soluble in solvents but cannot form any film capable of imparting an excellent texture.
Organopolysiloxanes having poly(N-acylalkyleneimine) segments are disclosed in EP-524612A, JP-A-3-287509 and JP-A-5-112423. Those publications relate to a polymer compound wherein the weight ratio of the organopolysiloxane segument/the poly(N-acylalkyleneimine) segument is 1/20 to 20/1, and the weight-average molecular weight is 500 to 500,000, for obtaining a modified silicone having characteristics of silicon oils and excellent solubility to polar solvents as well as water.
However, the concrete products disclosed in the above publications are those having a comparatively low molecular weight or having a low content of poly(N-acylalkyleneimine) segument, which can not always provide excellent texture when used for a hair care product.
EP-640643A further discloses that an organopolysiloxane grafted with the same type poly(N-acylalkyleneimine) is soluble in ethanol and can be easily added to hair cosmetics so as to achieve good setting performance. However, this material has no self-dispersibility in water. Even though an aqueous dispersion thereof is formed forcibly, it shows only a poor stability being unsuitable for cosmetics in practice.